Simpson jealous of Diaz and Mayer

Jessica Simpson is reportedly jealous of Cameron Diaz and her ex-lover John Mayer's current relationship.

Rumours surrounding a blossoming relationship between the Charlie's Angels star and the US rocker have apparently left Simpson feeling envious.

A source told US magazine: "She had her mouth open wide when she found out. She just freaked out. She thinks about him all the time. She is so not over him."

Despite the Newlyweds star splitting with Mayer back in May, she is still "really jealous" of his new lover, claims the insider.